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Date: Fri, 3 Oct 2008 17:54:25 +0200
From: Vegard Nossum <vegard.nossum@...il.com>
To: Jiri Slaby <jirislaby@...il.com>
Cc: Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH -tip] x86: fix virt_addr_valid() with
CONFIG_DEBUG_VIRTUAL=y (try 2)
On Fri, Oct 3, 2008 at 4:23 PM, Jiri Slaby <jirislaby@...il.com> wrote:
> Vegard Nossum napsal(a):
>> How about this? It would apply to tip/x86/mm-debug. Untested.
>
> It is wrong in my eyes -- it's workarounding of the real problem rather than
> fixing. virt_addr_valid() should be fixed/augmented to the full virtual
> address domain instead or not used for the purpose you need in kmemcheck.
>
> As it is now, it should be used only on direct mapping addresses (more
> concrete: kernel image space and physical mapping) and it returns
> semi-random values on the rest -- with CONFIG_DEBUG_VIRTUAL=y it screams
> instead of returning a bogus value.
>
Is this what you had in mind? If not, then I don't know how to do it :-)
It seems that it might be structured in a better way -- but that better way
eludes my imagination. Thanks for commenting!
Vegard
>From 320c68f94e1a2071c64ecc9db6358801bd0c1f0b Mon Sep 17 00:00:00 2001
From: Vegard Nossum <vegard.nossum@...il.com>
Date: Fri, 3 Oct 2008 15:58:50 +0200
Subject: [PATCH] x86: fix virt_addr_valid()
virt_addr_valid() calls __pa(), which calls __phys_addr(). With
CONFIG_DEBUG_VIRTUAL=y, __phys_addr() will kill the kernel if the
address *isn't* valid. That's clearly wrong for virt_addr_valid().
We also incorporate the debugging checks into virt_addr_valid().
Cc: Jiri Slaby <jirislaby@...il.com>
Cc: Andi Kleen <andi@...stfloor.org>
Signed-off-by: Vegard Nossum <vegardno@....ifi.uio.no>
---
arch/x86/kernel/doublefault_32.c | 2 +-
arch/x86/mm/ioremap.c | 37 +++++++++++++++++++++++++++++++++++--
include/asm-x86/page.h | 8 +++++++-
include/asm-x86/page_32.h | 4 ++--
4 files changed, 45 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c
index 395acb1..b4f14c6 100644
--- a/arch/x86/kernel/doublefault_32.c
+++ b/arch/x86/kernel/doublefault_32.c
@@ -66,6 +66,6 @@ struct tss_struct doublefault_tss __cacheline_aligned = {
.ds = __USER_DS,
.fs = __KERNEL_PERCPU,
- .__cr3 = __phys_addr_const((unsigned long)swapper_pg_dir)
+ .__cr3 = __pa_nodebug(swapper_pg_dir),
}
};
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 835e062..b20389d 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -45,6 +45,28 @@ unsigned long __phys_addr(unsigned long x)
}
EXPORT_SYMBOL(__phys_addr);
+bool __virt_addr_valid(unsigned long x)
+{
+ if (x >= __START_KERNEL_map) {
+ x -= __START_KERNEL_map;
+ if (x >= KERNEL_IMAGE_SIZE)
+ return false;
+ x += phys_base;
+ } else {
+ if (x < PAGE_OFFSET)
+ return false;
+ x -= PAGE_OFFSET;
+ if (system_state == SYSTEM_BOOTING
+ ? x > MAXMEM : !phys_addr_valid(x))
+ {
+ return false;
+ }
+ }
+
+ return pfn_valid(x >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(__virt_addr_valid);
+
#else
static inline int phys_addr_valid(unsigned long addr)
@@ -56,13 +78,24 @@ static inline int phys_addr_valid(unsigned long addr)
unsigned long __phys_addr(unsigned long x)
{
/* VMALLOC_* aren't constants; not available at the boot time */
- VIRTUAL_BUG_ON(x < PAGE_OFFSET || (system_state != SYSTEM_BOOTING &&
- is_vmalloc_addr((void *)x)));
+ VIRTUAL_BUG_ON(x < PAGE_OFFSET);
+ VIRTUAL_BUG_ON(system_state != SYSTEM_BOOTING &&
+ is_vmalloc_addr((void *) x));
return x - PAGE_OFFSET;
}
EXPORT_SYMBOL(__phys_addr);
#endif
+bool __virt_addr_valid(unsigned long x)
+{
+ if (x < PAGE_OFFSET)
+ return false;
+ if (system_state != SYSTEM_BOOTING && is_vmalloc_addr((void *) x))
+ return false;
+ return pfn_valid((x - PAGE_OFFSET) >> PAGE_SHIFT);
+}
+EXPORT_SYMBOL(__virt_addr_valid);
+
#endif
int page_is_ram(unsigned long pagenr)
diff --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index c915747..d4f1d57 100644
--- a/include/asm-x86/page.h
+++ b/include/asm-x86/page.h
@@ -179,6 +179,7 @@ static inline pteval_t native_pte_flags(pte_t pte)
#endif /* CONFIG_PARAVIRT */
#define __pa(x) __phys_addr((unsigned long)(x))
+#define __pa_nodebug(x) __phys_addr_nodebug((unsigned long)(x))
/* __pa_symbol should be used for C visible symbols.
This seems to be the official gcc blessed way to do such arithmetic. */
#define __pa_symbol(x) __pa(__phys_reloc_hide((unsigned long)(x)))
@@ -188,9 +189,14 @@ static inline pteval_t native_pte_flags(pte_t pte)
#define __boot_va(x) __va(x)
#define __boot_pa(x) __pa(x)
+/*
+ * virt_to_page(kaddr) returns a valid pointer if and only if
+ * virt_addr_valid(kaddr) returns true.
+ */
#define virt_to_page(kaddr) pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
-#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
+extern bool __virt_addr_valid(unsigned long kaddr);
+#define virt_addr_valid(kaddr) __virt_addr_valid((unsigned long) (kaddr))
#endif /* __ASSEMBLY__ */
diff --git a/include/asm-x86/page_32.h b/include/asm-x86/page_32.h
index 82b0109..deec501 100644
--- a/include/asm-x86/page_32.h
+++ b/include/asm-x86/page_32.h
@@ -71,11 +71,11 @@ typedef struct page *pgtable_t;
#endif
#ifndef __ASSEMBLY__
-#define __phys_addr_const(x) ((x) - PAGE_OFFSET)
+#define __phys_addr_nodebug(x) ((x) - PAGE_OFFSET)
#ifdef CONFIG_DEBUG_VIRTUAL
extern unsigned long __phys_addr(unsigned long);
#else
-#define __phys_addr(x) ((x) - PAGE_OFFSET)
+#define __phys_addr(x) __phys_addr_nodebug(x)
#endif
#define __phys_reloc_hide(x) RELOC_HIDE((x), 0)
--
1.5.5.1
--
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